STDEV.S

The STDEV.S function calculates the standard deviation in a sample set of data. Standard deviation is a measure of how much variance there is in a set of numbers compared to the average (mean) of the numbers. The STDEV.S function is meant to estimate standard deviation in a sample. If data represents an entire population, use the STDEV.P function. Note: STDEV.S replaces the older STDEV function, but has identical behavior. Although STDEV still exists for backwards compatibility, Microsoft recommends that people use the newer STDEV.S function instead. The table below summarizes the standard deviation functions provided by Excel.